Leap options saw their most active trading day of the year Friday at more than five-times the daily average over the past month, according to options-data firm Trade Alert LLC. And 95% of trading was in “call” options, which stand to reap large gains with AT&T’s $1.19 billion cash bid for the smaller wireless company.

Call options grant the right to buy shares at a set price by a designated date. Buyers of those contracts profit from a rise in shares to above the “strike” price.

“This seems to be a pretty ridiculous case of someone figuring it out,” said Henry Schwartz, president of options-data firm Trade Alert.

Out of 7,139 Leap Wireless options traded Friday, 6,789 contracts were calls. And activity in the bullish contracts options was also elevated over the prior two trading days, with volume at more than three times the daily average on both Wednesday and Thursday, according to the data.

Trading Friday was focused in July and August $9 call options, each contract of which grants the right to buy 100 Leap shares at $9 apiece through July 19 and Aug. 16, respectively. At the after-hours price of $16.60, those July contracts are set to bring in a $7.51 a share profit on a 9 cent per share purchase price—a more than 8,300% profit.

For one investor who picked up 672 contracts at that price at 3:42 p.m. EDT in a “sweep,” meaning the position was split into a number of smaller trades across a variety of options exchanges, a $16.60 share price could mean $504,672 in profits on a trade that cost $6,048 to set up.

Leap Wireless options were very rarely traded between 10:30 a.m. EDT and about 2:28 p.m. EDT Friday, Trade Alert’s Schwartz said. And the July $9 calls didn’t start trading until that 3:42 p.m. sweep trade, but more than 1,318 contracts traded before the close of trading.

The August $9 call saw 1,450 contracts traded Friday, and another 1,939 contracts and 879 contracts traded on Thursday and Wednesday, respectively. Also this week were July $7 call options, with 3,382 contracts traded in total in the Wednesday and Thursday sessions.